class Solution {
    public int minDistance(String word1, String word2) {
        int s1 = word1.length();
        int s2 = word2.length();

        int[][] dp = new int[s1 + 1][s2 + 1];

        for (int i = 0; i <= s1; i++) {
            dp[i][0] = i;
        }
        for (int i = 0; i <= s2; i++) {
            dp[0][i] = i;
        }

        for (int i = 1; i <= s1; i++) {
            for (int j = 1; j <= s2; j++) {
                if (word1.charAt(i - 1) == word2.charAt(j - 1)) {
                    dp[i][j] = dp[i - 1][j - 1];
                } else {
                    dp[i][j] = Math.min(Math.min(dp[i - 1][j] + 1, dp[i][j - 1] + 1), dp[i - 1][j - 1] + 1);
                }
            }
        }

        return dp[s1][s2];
    }
}